[Association between working in small-scale cultivated land as a daily-life task and the physical and cognitive functions among elderly people in hilly and mountainous areas].

AIM: This study aimed to verify whether working in cultivated land as a daily-life task contributes to the maintenance and improvement of physical and cognitive functions. METHODS: The participants were 91 elderly people of ≥65 years of age who owned cultivated land in the mountainous Koyadaira district in Tokushima Prefecture. Sex, age, body mass index (BMI), walking speed as a physical function, and the mini-mental status examination (MMSE) score as a cognitive function were measured and analyzed in addition to the total working hours per week (WH) in cultivated land. RESULTS: The participants were 31 males and 60 females (mean age 78.5±6.6 years). The average values of the evaluated variables were as follows: WH, 18.0±13.2; BMI, 23.4±3.0 kg/m2; walking speed, 0.95±0.28 m/s; and MMSE score, 26.6±3.1 points. In addition, the Mann-Whitney U test and the Chi-square test showed no significant differences between sexes for each item. A logistic regression analysis showed that WH was significantly associated with MMSE (1, ≥28 points; 0, <28 points), and the odds ratio was 1.054 (p=0.010) in the model adjusted for age and BMI, while it was not significantly associated with walking speed (1, ≥1 m/s; 0, <1 m/s). CONCLUSIONS: Working on small-scale cultivated land was significantly associated with the cognitive function but not the physical function. Routine work on small-scale cultivated land as a daily-life task would contribute to the suppression of cognitive decline in older people living in hilly and mountainous areas.

Assessment of potential clinical cascade between oral hypofunction and physical frailty: Covariance structure analysis in a cross-sectional study.

No report has yet examined the impact of oral hypofunction on physical frailty in relation to intra-relationships of physical frailty assessment items. The purpose of this study was to verify the potential of a clinical cascade between oral hypofunction and physical frailty, and especially to support the hypothesis that the influence of oral hypofunction on physical frailty is greater than the intra-relationships among elements of physical frailty and that sex differences significantly affect these relationships. The participants were 272 older adults (101 men and 171 women; mean age 75.1 ± 7.5 years). Maximum occlusal force (MOF) and oral dryness (OD), as indicators of oral hypofunction, and grip strength (GS) and walking speed (WS), as indicators of physical frailty, were measured. Mutual relationship of four variables was verified using covariance structure analysis. In men, three paths from MOF to WS and GS and from WS to GS were confirmed, and those from MOF to WS and from WS to GS were found to be significant (P < .01). In women, three paths from MOF to WS and GS and from WS to GS were also confirmed, as with the men, and those from MOF to WS and from MOF to GS were found to be significant (P < .01). Model adaptability was shown to be good for both men and women. The results suggest our hypothesis was verified, and it is expected that the early detection of oral hypofunction, that is MOF, may be important for assessing physical frailty, especially in women.

Prefrontal cortex activity induced by periodontal afferent inputs downregulates occlusal force.

The prefrontal cortex (PFC) plays an important role in several cognitive functions, such as planning, decision making, and social behavior. We previously reported that periodontal sensory input significantly increases PFC activity during the motor task of maintaining occlusal (biting) force. However, the relationships between periodontal sensation, PFC activity, and the performance of motor tasks have not been evaluated in detail. Therefore, using functional near-infrared spectroscopy, we investigated PFC activity by monitoring changes in cerebral blood flow (CBF) to specific areas of the PFC that corresponded to changes in occlusal force generated during four different biting tasks: (1) occlusion with the central incisor with an interocclusal distance of 5 mm (BI-5 mm); or (2) 10 mm (BI-10 mm); (3) occlusion with the first molars with an interocclusal distance of 5 mm (BM-5 mm), or (4) 10 mm (BM-10 mm). Occlusion of molars generated increased PFC regional CBF as the interocclusal distance decreased (BM-10 mm vs BM-5 mm). No significant differences in CBF during occlusion of incisors were found when comparing 5 mm and 10 mm intercostal distances (BI-5 mm vs BI-10 mm). The mean occlusal force generated by BM-5 mm occlusion was significantly lower than that generated by BM-10 mm occlusion. Taken together, our results suggest that the PFC decreases efferent signaling to motor units, to reduce occlusal force generated when periodontal sensation, which is greater when the interocclusal distance is reduced, is primarily responsible for maintaining occlusal force in the absence of sensations from the temporomandibular joint and muscle spindles.

[The application and usefulness of virtual reality aimed at encouraging an understanding of and reducing and eliminating prejudice towards dementia patients among local residents].

AIM: To demonstrate the usefulness of a virtual reality device that authentically portrays the emotions of dementia patients and their families (VR Dementia Experience) for encouraging an understanding of and reducing and eliminating prejudice towards dementia patients among local residents. METHOD: In Prefecture T, Town N, 85 residents of Neighborhood A were chosen as the intervention group, and 95 residents of Neighborhood B were chosen as the non-intervention group. The VR Dementia Experience was provided only to the residents of Neighborhood A. Residents of both neighborhoods completed a 35-item questionnaire regarding their degree of understanding and prejudice towards dementia patients before and after the intervention. RESULTS: Seventy-seven residents of Neighborhood A and 82 residents of Neighborhood B were analyzed. Their gender, age, and pre-intervention test baseline values were equivalent in the degree of understanding and prejudice. Significant increases were observed in 9 of 35 items for Neighborhood A residents (7 understanding-related, 2 prejudice-related) and 2 items for Neighborhood B residents (1 understanding-related, 1 prejudice-related). To ascertain the usefulness of the VR Dementia Experience, we compared the number of items with a significant increase: 9/35 (25.7%) in Neighborhood A and 2/35 (5.7%) in Neighborhood B. An effect (≥ 20%) was observed among the residents of Neighborhood A. Furthermore, after exposure to the VR Dementia Experience, the connection between understanding, prejudice, and dementia was strengthened among the residents of Neighborhood A compared to the residents of Neighborhood B. CONCLUSION: The VR Dementia Experience is a useful tool for encouraging an understanding of and reducing and eliminating prejudice towards dementia patients among local residents. However, to encourage the widespread usage of the technology, we should compare results with other public awareness campaigns as well as make improvements to the device and its VR content.

Development of a digital impression procedure using photogrammetry for complete denture fabrication.

OBJECTIVES: We developed an innovative procedure for digitizing maxillary edentulous residual ridges with a photogrammetric system capable of estimating three-dimensional (3D) digital forms from multiple two-dimensional (2D) digital images. The aim of this study was to validate the effectiveness of the photogrammetric system. MATERIALS AND METHODS: Impressions of the maxillary residual ridges of five edentulous patients were taken with four kinds of procedures: three conventional impression procedures and the photogrammetric system. Plaster models were fabricated from conventional impressions and digitized with a 3D scanner. Two 3D forms out of four forms were superimposed with 3D inspection software, and differences were evaluated using a least squares best fit algorithm. RESULTS: The in vitro experiment suggested that better imaging conditions were in the horizontal range of ± 15 degrees and at a vertical angle of 45 degrees. The mean difference between the photogrammetric image (Form A) and the image taken from conventional preliminarily impression (Form C) was 0.52 ± 0.22 mm. The mean difference between the image taken of final impression through a special tray (Form B) and Form C was 0.26 ± 0.06 mm. The mean difference between the image taken from conventional final impression (Form D) and Form C was 0.25 ± 0.07 mm. The difference between Forms A and C was significantly larger than the differences between Forms B and C and between Forms D and C. CONCLUSION: The results of this study suggest that obtaining digital impressions of edentulous residual ridges using a photogrammetric system is feasible and available for clinical use.

Part-Digitizing System of Impression and Interocclusal Record for Complete Denture Fabrication.

Few studies have reported the application of digital technology to removable dentures, particularly for the process of impression and interocclusal recording for complete denture fabrication. This article describes a part-digitizing system of impression and interocclusal records for complete denture fabrication. The denture foundation area in an edentulous mouth, including the border areas and residual ridge, is outlined by tracing the surfaces with a 3-D pen-type digitizer. Specialized trays for final impressions and interocclusal records were generated using computer-aided design and manufactured using the digital data. Final impression and interocclusal records were carried out using these specialized trays. The computer-aided method using preliminary digital impressions and specialized trays would be feasible for clinical use for complete denture fabrication.

Influence of matrix attachment installation load on movement and resultant forces in implant overdentures.

PURPOSE: This in vitro study investigated the effect of attachment installation conditions on the load transfer and denture movements of implant overdentures, and aims to clarify the differences among the three types of attachments, namely ball, Locator, and magnet attachments. MATERIALS AND METHODS: Three types of attachments, namely ball, Locator, and magnetic attachments were used. An acrylic resin mandibular edentulous model with two implants placed in the bilateral canine regions and removable overdenture were prepared. The two implants and bilateral molar ridges were connected to three-axis load-cell transducers, and a universal testing machine was used to apply a 50 N vertical force to each site of the occlusal table in the first molar region. The denture movement was measured using a G(2) motion sensor. Three installation conditions, namely, the application of 0, 50, and 100 N loads were used to install each attachment on the denture base. The load transfer and denture movement were then evaluated. RESULTS: The resultant force decreased with increasing installation load for all attachments. In particular, the resultant force on implants on the loading side of the Locator attachment significantly decreased when the installation load was increased from 0 to 50 N, and that for magnetic attachment significantly decreased when the installation load was increased from 50 to 100 N. For the residual ridges on the loading side, the direction of the forces for all attachments changed to downward with increasing installation load. Furthermore, the yaw Euler angle increased with increasing installation load for the magnetic attachment. CONCLUSIONS: Subject to the limitations of this study, the use of any installation load greater than 0 N is recommended for the installation of ball and Locator attachments on a denture base. Regarding magnetic attachments, our results also recommend installation on a denture base using any installation load greater than 0 N, and suggest that the resultant force acting on the implant can be decreased by increasing the installation load; however, a large installation load of 100 N should be avoided when installing the attachment on the denture base to avoid increasing the denture movement.

Do sensation differences exist between dental implants and natural teeth?: a meta-analysis.

OBJECTIVE: The purpose of this systematic review was to survey evidence pertaining to the sensation differences between natural teeth and osseointegrated dental implants. MATERIAL AND METHODS: Using the MEDLINE (online PubMed) database, Cochrane Library, and Scientific Citation index, we performed a systematic search of articles. We used the following search terms: "perception or sensation and dental implant." The systematic review of the extracted articles was performed to see the sensation differences between natural teeth and dental implants. RESULTS: A total of six studies on oral sensation, "tactile sensibility," and "thickness discrimination" were included in the meta-analysis. As to the "tactile sensibility", all studies indicated the threshold levels of the implants were about 4-20 times higher than that of natural teeth. The tactile sensibility of an implant was significantly higher than that of a natural tooth, with an standardized mean difference (SMD) of 8.3619 (95% CI, 6.3920-10.3317) and a P < 0.0001. As to the "thickness discrimination", all studies indicated the threshold levels of implants were about 1.2-2.3 times higher than that of natural teeth. The thickness discrimination was significantly higher than that of natural teeth with an SMD of 1.2368 (95% CI, 0.8699-1.6038) and a P < 0.0001. CONCLUSION: This meta-analysis suggested that both tactile sensibility and thickness discrimination thresholds of implants were significantly higher than those of natural teeth. This meta-analysis reconfirms that sensation differences between dental implants and natural teeth exist.

Mouth breathing reduces oral function in adolescence.

Although humans breathe naturally through the nostrils, mouth breathing in children has recently gathered attention. In this study, we hypothesized that tongue function and its related maxillofacial morphology would affect breathing in adolescence. To verify this hypothesis, we examined the association between breathing patterns, including mouth and nasal breathing; oral functions, including tongue motor function; and craniofacial morphology during adolescence, which has not been investigated till date. C3-H, which indicates the anteroposterior position of the hyoid bone in relation to the third cervical vertebra, was significantly smaller in mouth-breathers than in nasal-breathers. Lip-closing force, tongue pressure, and masticatory efficiency were lower in the order of nasal-breathers, oronasal-breathers, and mouth-breathers, and the values for mouth-breathers were significantly lower than those for nasal-breathers. Tongue pressure alone was identified as a significant independent variable, with an odds ratio of 1.063 (95% confidence interval, 1.006-1.123; p < 0.05). Our results indicate a relationship between mouth breathing and the lip-closing force, tongue pressure, and masticatory efficiency, as well as the significance of tongue pressure on mouth breathing in adolescents. The findings highlight the importance of clarifying the pathophysiology of mouth breathing and its underlying causes.

Social frailty as a predictor of all-cause mortality and functional disability: a systematic review and meta-analysis.

The association between social frailty and adverse health outcomes, especially mortality and functional disability, which are essential health outcomes, has not been systematically summarized or meta-analyzed. In this study, we conducted a systematic review and meta-analysis of the impact of social frailty on all-cause mortality and functional disability, while addressing the components of social frailty. In this study, social frailty was operationally defined in alignment with the previous literature, as follows: "a state of increased vulnerability to the interactive back-and-forth of the community, including general resources, social resources, social behaviors, and needs." Hazard ratios or odds ratios described in each selected literature were used as the meta-analytic results. Considering the impact of social frailty on all-cause mortality, the hazard ratio was 1.96 (95% CI 1.20-3.19), indicating a significant association between the two but high heterogeneity. The hazard and odds ratios for the impact of social frailty on functional disability were 1.43 (95% CI 1.20-1.69) and 2.06 (95% CI 1.55-2.74), respectively. A significant association was found between social frailty and functional disability; both hazard and odds ratios were found, and low heterogeneity between these articles was observed. These results highlight the importance of assessing social frailty using more standardized methods and examining its effects on various health outcomes.

Biopsychosocial Consideration of Ikigai in Older Adults in Japan through a Cross-Sectional Study.

Ikigai-a Japanese concept that includes elements such as life's purpose and meaning-has been reported to be associated with various systemic health conditions, such as the risk of developing physical dysfunction or death in older adults. However, there are no reports that comprehensively examine the psychological and social aspects of Ikigai. We attempted to clarify the characteristics of Ikigai by examining it from a biopsychosocial model using physical, psychological, and social perspectives through a cross-sectional study on sarcopenia, frailty and healthy life expectancy in a hilly and mountainous area of Japan. Koyadaira in Mima City, which is located in a hilly and mountainous region on Shikoku Island in Japan, was targeted. This cross-sectional study included 105 outpatients aged 65 and over, with an average age of 79.02 ± 6.91 years. Ikigai (self-rating score on a scale of 0 (no Ikigai) to 5 (the highest Ikigai)) participants' level of physical activity (the Physical Activity Scale for the Elderly, PASE), degree of depression (the Geriatric Depression-15 Scale, GDS-15), cognitive function (the Mini-Mental State Examination, MMSE) and social isolation (the abbreviated Lubben Social Network Scale, LSNS-6) was assessed. Significant positive correlations were found between PASE and MMSE. The LSNS-6 significantly correlated with the MMSE and GDS-15. In a path model, out of four paths from PASE, GDS-15, MMSE, and LSNS-6 to Ikigai, the path from the GDS-15 alone was significant (correlation coefficient -0.271, p < 0.01). The adaptability of this model was good. This study indicates that depressive status has a large impact on Ikigai, along with physical, cognitive, and social conditions; thus, it is appropriate to consider that an affective psychological status, such as depressive symptoms, is a fundamental condition for having Ikigai.

Can Measurement of Ultrasonic Echo Intensity Predict Physical Frailty in Older Adults?

Echo intensity (EI) of the tongue in ultrasonography is an easy and quantitative assessment of tongue function. Elucidating the relationship between EI and frailty, is expected to aid in the early detection of frailty and oral hypofunction in older adults. We assessed tongue function and frailty in older outpatients visiting a hospital. The subjects were 101 individuals aged 65 or older (35 men and 66 women, mean age 76.4 ± 7.0 years). Tongue pressure and EI were measured as assessments of tongue function and grip strength, and Kihon Checklist (KCL) scores were measured as assessments of frailty. In women, a significant correlation was not found between the mean EI and grip strength, whereas a significant correlation was noted between each score of the KCL and the mean EI; the scores increased as the mean EI increased. A significant positive correlation was found between tongue pressure and grip strength, but no significant correlation was observed between tongue pressure and the KCL scores. In men, no significant correlation was found between tongue assessments and frailty, except for a significant positive correlation between tongue pressure and grip strength. The results of this study suggest that EI of the tongue is positively associated with physical frailty in women and may be useful for early detection of physical frailty status.

Effective use of an extraoral vacuum in preventing the dispersal of particulate matter from metal dental materials.

OBJECTIVES: When dentists adjust prostheses at the dental chairside, particulate matter (PM) from the dental material is dispersed. Little is known about the effective use of an extraoral vacuum (EOV) in preventing PM dispersal. This study aimed to evaluate the effective use of an EOV in preventing the dispersal of metal PM in dental offices. METHODS: The following experimental conditions were planned: the distance from the EOV to the metallic materials (50, 100, 150, and 200 mm), the horizontal angle between the long axis of the micromotor handpiece and EOV (0°, 45°, and 90°), and the operating time of the EOV (during grinding, during grinding and 1 min thereafter, during grinding and the preceding 1 min, 1 min before and after grinding, and during grinding). Carborundum and silicone points were used for grinding and PM dispersal. Diameters (0.3, 0.5, 1.0, and 3.0 µm) were measured using a laser particle counter. RESULTS: Depending on the instrument used to grind, there were undetectable PMs of different diameters (Carborundum point: 0.3 and 0.5 µm, Silicone point: 0.3 µm). PMNs were reduced as the distance from the EOV to metal materials decreased. Operating the EOV before grinding along the long axis of the micromotor handpiece was effective in reducing the PMNs. CONCLUSION: PMNs dispersed when grinding metals were effectively reduced by positioning the EOV closer to the grinding surface (within 150 mm) along the long axis of the micromotor handpiece and operating the EOV before grinding.

2-methacryloyloxyethyl phosphorylcholine polymer treatment prevents Candida albicans biofilm formation on acrylic resin.

PURPOSE: We aimed to evaluate the effectiveness of photoreactive 2-methacryloyloxyethyl phosphorylcholine (MPC) in inhibiting Candida albicans biofilm formation on polymethyl methacrylate (PMMA) and assess its mechanism and need for re-application by evaluating its interaction with salivary mucin and durability during temperature changes. METHODS: PMMA discs were used as specimens. The MPC coating was applied using the spray and cure technique for the treatment groups, whereas no coating was applied to the control. The MPC treatment (MT) groups were further differentiated based on the number of thermal cycles involved (0, 1000, 2500, and 5000). The optical density was measured to assess mucin adsorption (MA). Contact angle (CA) was calculated to evaluate surface hydrophilicity. The presence of MPC components on the PMMA surface was assessed using X-ray photoelectron spectroscopy (XPS). C. albicans biofilms were evaluated qualitatively (scanning electron microscope images) and quantitatively (colony-forming units (CFUs)). Statistical analysis was conducted using two-way analysis of variance and Tukey's multiple comparison test. RESULTS: MA rate and CA increased significantly in the MT groups, which exhibited significantly fewer CFUs and thinner biofilms than those of the control group. Based on the XPS, MA, and CFU evaluations, the durability and efficacy of the MPC coating were considered stable up to 2500 thermal cycles. Additionally, a significant interaction was observed between mucin concentration and MPC efficacy. CONCLUSIONS: The photoreactive MPC coating, which was resistant to temperature changes for approximately 3 months, effectively prevented C. albicans biofilm formation by modifying surface hydrophilicity and increasing mucin adsorption.

Stress Reduction Effects during Block-Tapping Task of Jaw in Healthy Participants: Functional Near-Infrared Spectroscopy (fNIRS) Measurements of Prefrontal Cortex Activity.

The purpose of this study was to explore the influence of simple jaw opening and closing task of chewing movements on the activities of the prefrontal cortex (PFC) from the viewpoint of stress reduction. We measured cerebral blood flow (CBF) in the PFC during a block-tapping task of the jaw in healthy participants. Eleven young healthy individuals with normal dentition (7 males and 4 females, mean age 28.0 ± 3.7 years) volunteered for this study. CBF was measured using a wearable, functional near-infrared spectroscopy device. Measurements were taken using the central incisors and first molars at interocclusal distances of 5 and 10 mm. The participants were asked to bite a hard/soft block. CBF in all conditions showed limited variability or decreasing trend compared to resting state before the task. The main effect was observed for interocclusal distance (p = 0.008), and there were no significant differences for measurement area of the PFC, tooth type, and material type. An interaction was found between tooth type and material type. In conclusion, these results suggest that simple and rhythmical chewing motion has an effect of reducing CBF in the PFC and resting the PFC, which is an especially notable aspect of periodontal sensory information in the molar.

Application of artificial intelligence in the dental field: A literature review.

PURPOSE: The purpose of this study was to comprehensively review the literature regarding the application of artificial intelligence (AI) in the dental field, focusing on the evaluation criteria and architecture types. STUDY SELECTION: Electronic databases (PubMed, Cochrane Library, Scopus) were searched. Full-text articles describing the clinical application of AI for the detection, diagnosis, and treatment of lesions and the AI method/architecture were included. RESULTS: The primary search presented 422 studies from 1996 to 2019, and 58 studies were finally selected. Regarding the year of publication, the oldest study, which was reported in 1996, focused on "oral and maxillofacial surgery." Machine-learning architectures were employed in the selected studies, while approximately half of them (29/58) employed neural networks. Regarding the evaluation criteria, eight studies compared the results obtained by AI with the diagnoses formulated by dentists, while several studies compared two or more architectures in terms of performance. The following parameters were employed for evaluating the AI performance: accuracy, sensitivity, specificity, mean absolute error, root mean squared error, and area under the receiver operating characteristic curve. CONCLUSION: Application of AI in the dental field has progressed; however, the criteria for evaluating the efficacy of AI have not been clarified. It is necessary to obtain better quality data for machine learning to achieve the effective diagnosis of lesions and suitable treatment planning.

Novel Magnetic Attachment System Manufactured Using High-Frequency Heat Treatment and Stamp Technique: Introduction and Basic Performance.

Recently, a novel magnetic attachment with extremely low cost and high performance was developed. This article aims to introduce a novel magnetic attachment and to evaluate its basic eligibility for denture retention in clinical practice. The novel magnetic attachment system used in this study was the direct-bonding root-keeper-type Magteeth™ MT800 (MagneDesign, Nagoya, Japan). The retentive force without displacement (position 0) and after horizontal displacement to positions 0.5, 1, 1.5, 2, 2.5, and 3 mm were measured. The values relative to the retentive force without displacement were gradually decreased to 82.7 ± 16.3%, 68.8 ± 17.1%, 62.4 ± 15%, 47.2 ± 13.1%, 35.7 ± 9.9%, and 20.7 ± 6.5%, respectively. The retentive force and magnetic field strength did not change significantly after the load test (100 N load, 10,000 times). No new gap between the metal and resin was found in the root keeper- and magnet assembly-embedded blocks after the load test. Some scratches on magnetic assembly and root keeper surface, while no change in the resin texture after the load test were observed. Based on the findings of this preliminary study, this novel low-cost magnetic attachment exhibited favorable retention, strength, and durability for clinical use.